I know how you are feeling. I have had the same thing many times. This too will pass. What you need to realize is that your body is made to breathe whether or not we think about it. So you can rest assured that when you fall asleep your breathing will be fine. The more you think about it the worst it becomes(I know your thinking I can't help,nor do I want to think about it) Try to find other things to do while you fall asleep. I used to add and subtract numbers in my head. Try to tell yourself that this will pass just like last time.